It’s a pretty safe bet to say that most people interact with glass frequently every day of their lives. Whether it is your car’s windshield or the screen of your smartphone, glass plays an integral role in modern society.
Glass manufacturing is incredible, especially when considering the enormity of some glass manufacturing facilities. That being said, not too many people think about everything that goes into how glass is actually made:
- What happens during the manufacturing process?
- How is glass formed and cut to size on a large scale?
- Which materials does the industry rely on?
One material that every facility uses, is carbon graphite. Carbon graphite's properties make it ideal for use in glass making. However, before we can understand carbon grahpite's role in this process, we must first take a step back and gain a bird's eye view of how glass production works.
Float Glass Production Under the Magnifying Glass
Float glass production is a term used to describe the manufacturing of sheet glass, which is used in a variety of applications ranging from building materials to widescreen televisions. Sheet glass is comprised of a variety of raw materials including sand, dolomite, lime, and cullet (which is a term used to describe shards of broken glass that are recycled back into the glass making process).
These raw materials are mixed and then melted inside a furnace at temperatures up to 3,000°F. These furnaces often run 24/7 for years on end, which is an engineering feat in and of itself. After being processed in the furnace, the molten glass is fed onto a bath of molten tin. Molten tin has a higher density than that of molten glass, which allows the glass to spread out, or “float”, on top of the tin and flatten into a sheet.
The glass is then slowly cooled until it solidifies – this is called annealing. At this point, the glass can either be cut to size and packaged for delivery or processed even further into safety glass. If the glass is going to be used in a safety critical application (i.e. car windshields, glass tables, etc.), it will need to be tempered. This essentially means that the glass is heated and then cooled under pressure, a process commonly referred to as quenching. When glass is quenched, the outer surface cools much more quickly than the inside, causing the outside to go into compression and the inside to go into tension.
This makes tempered glass much stronger than plain annealed glass. As an added benefit, if tempered glass does break, it will break into small, relatively harmless chunks as opposed to jagged shards. The next time you are staring out the passenger side window on a long road trip, take a look at the printed text often located on the bottom right side of the window. In all likelihood, it will mention that the glass is tempered.
How Glass Production Relies on Carbon Graphite Materials
So, where does carbon graphite play a role in this process? The short answer is – everywhere!
- Carbon graphite bearings can be utilized as the glass’s raw material is fed into the furnace.
- Carbon graphite rollers can be used to transport semi-molten glass as it is quenched or tempered.
- Carbon graphite molds can be used to form the glass into the desired final dimensions.
But carbon graphite is not restricted to sheet glass production – it can be used wherever glass is being annealed, tempered, or shaped. For instance, graphite spools are often used to guide fiber optic cables (which are, in essence, tiny strands of glass) as they anneal into their finished shape. Many glass artisans even use graphite tongs to handle their blown glass creations.
The 5 Properties that Make Carbon Graphite Perfect for Glass Production
Carbon graphite’s incredible material properties make it the perfect choice for extreme environments of severe applications like glass production. The table below shows just how glass manufacturers take advantage of these properties during glass production:
| MATERIAL PROPERTY | ADVANTAGE IN GLASS APPLICATIONS |
| Not Wetted by Glass | Molten glass will not adhere to CG during processing. |
| Soft | CG is a 2 on the Moh’s Scratch Hardness Scale (just above Talc), so it will not scratch glass. |
| High Thermal Conductivity | Heat travels quickly through CG, so molten glass will not be exposed to sudden uneven temperature distributions when in contact with CG during annealing or tempering. |
| High Oxidation Resistance | CG can withstand extended exposure to elevated temperatures without material degradation. |
| Self-Lubricating | No need for oil or grease lubricants in application. |
Carbon graphite manufacturers are constantly developing new material grades to satisfy incredible applications like glass production. If you are looking for a material solution for your glass application, carbon graphite may be the clear choice.
Whatever your problem, our engineers always see the glass as half full. We’re happy to discuss and figure out a solution with you today.
